Rounding and Estimation
Objectives:
…to round numbers to specific place values
…to estimate sums, differences, products and quotients
Assessment Anchor:
7.A.3.1 – Apply estimation strategies to a variety of problems.
A Sampling of Place Values
2,345,109.8672
NOTES
1.
Locate the specific place value in the number you are looking at.
2.
Go one spot to the right and use this digit as your decision digit. a.
IF it is a 0, 1, 2, 3, or 4 …keep the place value number the same b.
IF it is a 5, 6, 7, 8, or 9 …increase the place value number by one c.
Change all the digits to the RIGHT of the place value to ZEROS!
***SPECIAL SITUATION!! - When the place value has a (9), and you need to increase it by one…Change the (9) to a (0) and proceed to the left and increase THAT digit by one as well.

Rounding and Estimation
EXAMPLES
Round to the nearest TENTHS place:
83.521 9.8523 187.98
Round to the nearest HUNDREDS place:
3,578 17,390.219 328.1
Round to the nearest ONES place (whole number):
835.09 199.542 0.2998
ESTIMATE – an answer that is close to the real answer; to quickly perform an approximation
Estimating Sums and Differences:
1. Pick a place value to round the numbers.
2. Add or subtract these rounded numbers to get your ESTIMATE!
1) 548.3 + 37.91
550 Rounded to tens place
+ 40
590 ESTIMATE
548.30
+ 37.91
ACTUAL 586.21

Rounding and Estimation
2) 57.34 – 24.9
57
– 25
32
Rounded to whole number
ESTIMATE ACTUAL
57.34
– 24.90
32.44
3) 95.72 + 189.5
ESTIMATE ACTUAL
4) 4,582.4 – 2,119.73
ESTIMATE ACTUAL
Estimating Products:
1. Pick a place value to round the numbers. CAN BE DIFFERENT FOR
EACH NUMBER!!
2. Multiply these rounded numbers to get your ESTIMATE!
5) 49.23 × 6.2
50
× 6
Rounded to tens place 49.23
Rounded to whole number × 6.2
300 ESTIMATE 9846
295380
ACTUAL 305.226

Rounding and Estimation
6) 12.14 × 21.5
ESTIMATE
7) 3,015.4 × 7.8
ESTIMATE
ACTUAL
ACTUAL
COMPATIBLE NUMBERS – numbers that can be divided
evenly
Estimating Quotients:
1. Choose numbers that are close to the original numbers, but are
COMPATIBLE (able to be divided easily).
2. Divide these compatible numbers to get your ESTIMATE!
8) 54.79 ÷ 8.8 9) 141.92 ÷ 11.5
54 ÷ 9 compatible numbers
6 ESTIMATE
144 ÷ 12
12

Rounding and Estimation
10) 312.5 ÷ 19.74
300 ÷ 20 compatible numbers
11) 78.192 ÷ 5.08
80 ÷ 5
ESTIMATE 16 15
12) 62.1 ÷ 9.18 13) 63.5 ÷ 6.45
14) 459.21÷ 47.9 15) 245.6 ÷ 55.9
“If you round the DIVISOR to something
nice, it will be easy to find a multiple of
that number that is closest to the
DIVIDEND!